> ## Documentation Index
> Fetch the complete documentation index at: https://docs.labelbox.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Hard stop a session immediately

> Stops the session immediately and schedules durable sandbox teardown. The response confirms the session stopped; sandbox cleanup may continue asynchronously and is retried. A session that already reached a terminal status with no pending cleanup is left as it is, so the call is safe to repeat.



## OpenAPI

````yaml /recursion/openapi.yaml post /managed-agents/v1/sessions/{sessionId}/cancel
openapi: 3.1.0
info:
  title: Managed Agents API
  version: 0.14.0
  description: >-
    The Recursion Managed Agents REST API. Authenticate with a Recursion API key
    as a bearer token. An organization-scoped key acts in its own organization
    and needs nothing else; a tenant-scoped key must also send
    `x-organization-id` with an organization id or `default`. Field names follow
    each operation's published schema.
servers:
  - url: https://api.recursion.labelbox.com
security:
  - bearerAuth: []
paths:
  /managed-agents/v1/sessions/{sessionId}/cancel:
    post:
      tags:
        - Sessions
      summary: Hard stop a session immediately
      description: >-
        Stops the session immediately and schedules durable sandbox teardown.
        The response confirms the session stopped; sandbox cleanup may continue
        asynchronously and is retried. A session that already reached a terminal
        status with no pending cleanup is left as it is, so the call is safe to
        repeat.
      operationId: managedAgentsCancelSession
      parameters:
        - description: >-
            Session id (UUID) as returned by managedAgentsStartSession or
            managedAgentsListSessions.
          in: path
          name: sessionId
          required: true
          schema:
            description: >-
              Session id (UUID) as returned by managedAgentsStartSession or
              managedAgentsListSessions.
            format: uuid
            type: string
        - $ref: '#/components/parameters/RecursionTenantId'
        - $ref: '#/components/parameters/RecursionOrganizationId'
      responses:
        '200':
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CancelledResponse'
          description: >-
            Response body of POST
            /managed-agents/v1/sessions/{sessionId}/cancel. Cancel is terminal
            for the run but not for the record: the session is stopped and the
            sandbox torn down, while the session, its events, and its outcomes
            remain readable. The session row itself is removed from reads only
            by the separate soft-delete endpoint.
          headers:
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
        '400':
          description: Bad Request.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ManagedAgentsApiErrorInvalidRequest'
                x-recursion-error-codes:
                  - invalid_request
          headers:
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
        '401':
          description: Unauthorized.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ManagedAgentsApiErrorUnauthorized'
                x-recursion-error-codes:
                  - unauthorized
          headers:
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
        '403':
          description: Forbidden.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ManagedAgentsApiErrorForbidden'
                x-recursion-error-codes:
                  - forbidden
          headers:
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
        '404':
          description: Not Found.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ManagedAgentsApiErrorNotFound'
                x-recursion-error-codes:
                  - not_found
          headers:
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
        '409':
          description: Conflict.
          content:
            application/json:
              schema:
                $ref: >-
                  #/components/schemas/ManagedAgentsApiErrorEvaluationCancellationPending
                x-recursion-error-codes:
                  - evaluation_cancellation_pending
          headers:
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
        '413':
          description: Payload Too Large.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ManagedAgentsApiErrorPayloadTooLarge'
                x-recursion-error-codes:
                  - payload_too_large
          headers:
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
        '415':
          description: Unsupported Media Type.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ManagedAgentsApiErrorUnsupportedMediaType'
                x-recursion-error-codes:
                  - unsupported_media_type
          headers:
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
        '429':
          headers:
            Retry-After:
              description: When to retry, as delay seconds or an HTTP date.
              schema:
                type: string
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
          description: Too Many Requests.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ManagedAgentsApiErrorRateLimitExceeded'
                x-recursion-error-codes:
                  - rate_limit_exceeded
        '500':
          description: Internal Server Error.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ManagedAgentsApiErrorInternalError'
                x-recursion-error-codes:
                  - internal_error
          headers:
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
        '502':
          description: A dependent service returned an invalid response.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ManagedAgentsApiErrorDependencyFailure'
                x-recursion-error-codes:
                  - bad_gateway
          headers:
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
        '503':
          headers:
            Retry-After:
              description: When to retry, as delay seconds or an HTTP date.
              schema:
                type: string
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
          description: Service Unavailable.
          content:
            application/json:
              schema:
                oneOf:
                  - $ref: >-
                      #/components/schemas/ManagedAgentsApiErrorManagedAgentsUnavailable
                  - $ref: >-
                      #/components/schemas/ManagedAgentsApiErrorServiceUnavailable
                discriminator:
                  propertyName: code
                  mapping:
                    managed_agents_unavailable: >-
                      #/components/schemas/ManagedAgentsApiErrorManagedAgentsUnavailable
                    service_unavailable: >-
                      #/components/schemas/ManagedAgentsApiErrorServiceUnavailable
                x-recursion-error-codes:
                  - managed_agents_unavailable
                  - service_unavailable
        '504':
          headers:
            Retry-After:
              description: When to retry, as delay seconds or an HTTP date.
              schema:
                type: string
            recursion-organization-id:
              $ref: '#/components/headers/RecursionOrganizationId'
            recursion-tenant-id:
              $ref: '#/components/headers/RecursionTenantId'
          description: A dependent service timed out.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ManagedAgentsApiErrorDependencyTimeout'
                x-recursion-error-codes:
                  - gateway_timeout
components:
  parameters:
    RecursionTenantId:
      name: x-tenant-id
      in: header
      required: false
      description: >-
        Optional tenant consistency check. When present, it must name the tenant
        bound to the API key, including when x-organization-id is `default`.
      schema:
        type: string
        minLength: 1
    RecursionOrganizationId:
      name: x-organization-id
      in: header
      required: false
      description: >-
        Organization in which to act. Required for a tenant-scoped API key.
        Optional for an organization-scoped key, where it must name that same
        organization. The value may be an organization id or `default`.
      schema:
        type: string
        minLength: 1
  schemas:
    CancelledResponse:
      description: >-
        Response body of POST /managed-agents/v1/sessions/{sessionId}/cancel.
        Cancel is terminal for the run but not for the record: the session is
        stopped and the sandbox torn down, while the session, its events, and
        its outcomes remain readable. The session row itself is removed from
        reads only by the separate soft-delete endpoint.
      properties:
        cancelled:
          description: >-
            Always true. The session was stopped and the sandbox closed;
            failures are HTTP errors instead, so this field never reports false.
            It is also true when the session had already reached a terminal
            state, making cancel safe to retry.
          type: boolean
      required:
        - cancelled
      type: object
      additionalProperties: false
    ManagedAgentsApiErrorInvalidRequest:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - invalid_request
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorUnauthorized:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - unauthorized
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorForbidden:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - forbidden
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorNotFound:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - not_found
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorEvaluationCancellationPending:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - evaluation_cancellation_pending
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorPayloadTooLarge:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - payload_too_large
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorUnsupportedMediaType:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - unsupported_media_type
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorRateLimitExceeded:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - rate_limit_exceeded
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorInternalError:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - internal_error
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorDependencyFailure:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - bad_gateway
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorManagedAgentsUnavailable:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - managed_agents_unavailable
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorServiceUnavailable:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - service_unavailable
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorDependencyTimeout:
      type: object
      properties:
        code:
          type: string
          minLength: 1
          description: Stable machine-readable error code.
          enum:
            - gateway_timeout
        message:
          type: string
          minLength: 1
          description: Human-readable error message.
        details:
          $ref: '#/components/schemas/ManagedAgentsApiErrorDetails'
          description: >-
            Optional structured error details. Reserved transport fields are
            typed; code-specific fields remain forward compatible.
      required:
        - code
        - message
      additionalProperties: false
      description: Standard flat error response.
    ManagedAgentsApiErrorDetails:
      type: object
      properties:
        field:
          description: >-
            Request field or header responsible for the error, when one can be
            identified.
          type: string
        issues:
          description: >-
            Boundary-validation failures as path-prefixed human-readable
            messages.
          type: array
          items:
            type: string
        requestId:
          description: Request correlation identifier for support and log lookup.
          type: string
        retryable:
          description: >-
            Server advice about failure transience. `true` means transient,
            `false` means non-transient, and absence gives no advice. Automatic
            replay is allowed only when this field is not `false` and the
            operation-specific retry and idempotency contract permits replay.
          type: boolean
      additionalProperties:
        $ref: '#/components/schemas/PlatformSafeJsonValue'
      description: >-
        Optional structured error details. Reserved transport fields are typed;
        code-specific fields remain forward compatible.
    PlatformSafeJsonValue:
      description: >-
        A JSON value whose integer members stay within the exact ECMAScript
        safe-integer range at every nesting level.
      oneOf:
        - type: 'null'
        - type: boolean
        - type: string
        - type: integer
          minimum: -9007199254740991
          maximum: 9007199254740991
        - type: number
          not:
            type: integer
        - type: array
          items:
            $ref: '#/components/schemas/PlatformSafeJsonValue'
        - additionalProperties:
            $ref: '#/components/schemas/PlatformSafeJsonValue'
          type: object
  headers:
    RecursionOrganizationId:
      description: Organization id resolved for this request.
      schema:
        type: string
        minLength: 1
    RecursionTenantId:
      description: Tenant id resolved for this request.
      schema:
        type: string
        minLength: 1
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: A Recursion API key, created in the console under API keys.

````